Bills RBs LeSean McCoy, Karlos Williams miss practice Thursday

LeSean McCoy #25 of the Buffalo Bills on the sideline during NFL game action against the Indianapolis Colts at Ralph Wilson Stadium on September 13, 2015 in Orchard Park, New York. (Photo by Tom Szczerbowski/Getty Images) The Miami Dolphins defense fails to stop Buffalo Bills' Karlos Williams as he scores a touchdown during the fourth quarter on Sunday, Sept. 27, 2015, at Sun Life Stadium in Miami Gardens, Fla. (Charles Trainor Jr./Miami Herald/TNS via Getty Images)

Buffalo Bills running backs LeSean McCoy and Karlos Williams don't appear as though they'll be on the field Sunday against the Tennessee Titans.

Both McCoy and Williams missed practice on Thursday due to injury. McCoy is dealing with a lingering hamstring issue dating back to mid-August and has said he won't return until he's 100 percent.

Williams, however, sustained a concussion in Sunday's loss and is uncertain to play this week. Rex Ryan said it's a "reach" for him to be on the field against the Titans as he's still in concussion protocol.